Trendlines and Diagonal Levels
Sloping support and resistance, and their limits.
Overview
A trendline is support or resistance that moves. It connects a series of higher lows in an uptrend or lower highs in a downtrend, describing the rate at which a trend is progressing.
How to Draw One
A trendline requires at least two points to draw and a third touch to confirm. Until price has respected the line three times, it is a hypothesis rather than a level.
- Uptrend line: Connects successive higher lows, acting as support
- Downtrend line: Connects successive lower highs, acting as resistance
Slope Tells You Something
The angle of a trendline carries information. A shallow line describes a sustainable trend that can continue for a long time. A very steep line describes a move that is accelerating, and acceleration is rarely maintained.
When price breaks a steep trendline, it frequently continues in the original direction at a shallower angle rather than reversing outright.
Trendlines Versus Horizontal Levels
Horizontal levels are objective in a way trendlines are not. Two traders will usually mark the same horizontal level, but can draw very different trendlines on the same chart.
For that reason, most traders treat horizontal levels as primary and trendlines as supporting context.
Channels
Drawing a parallel line on the opposite side of price creates a channel, which frames both where a trend finds support and where it tends to stall. Price moving outside a channel signals either acceleration or exhaustion, depending on direction.
Psychology Behind Trendlines
A trendline works because participants extrapolate. Having seen price bounce at a rising line twice, traders anticipate it happening again and place orders accordingly, which can make the expectation partially self-fulfilling.
Confirmation Signals
- Three or more clean touches
- Touches spaced out in time rather than clustered together
- Reactions that produced meaningful moves, not just brief pauses
- The line remaining valid on a higher timeframe
Weaknesses & Limitations
- Highly subjective; the same chart supports many valid lines
- Easy to redraw to fit whatever price has just done
- Log and linear scaling produce different lines over large ranges
- Steep trendlines break routinely without signalling a reversal
Example Use
A trader identifies a rising trendline with three touches on the 4H chart. Rather than buying the fourth touch blindly, they wait for confluence with a horizontal level, and only take the trade where the two coincide.
Risk Management Notes
Because a trendline moves, so does the stop derived from it. Decide before entering whether your invalidation is the line itself or a fixed price beneath it, and do not switch between the two once you are in the trade.